THE Bureau of Meteorology says the Clarence River's peak of 8.08m at Grafton around 11am was the highest seen since records began in 1839.

The previous record was 7.9m measured in 1890.

Meanwhile, Premier Barry O'Farrell has told reporters in Grafton the worst of the floods in NSW has now passed.

He said the state government would work with the local council and other relevant authorities to ensure the flood mitigation measures continued to work.

4pm: Ten local government areas hit by flooding in northern NSW have been declared natural disaster areas, allowing relief funds to flow to assist in recovery.

Prime Minister Julia Gillard and NSW Premier Barry O'Farrell made the announcement on Tuesday for the joint funding from the federal and NSW governments.

Natural disaster assistance would be available to affected residents, small business owners and primary producers in the Ballina, Bellingen, Byron, Tweed and Nambucca shires, the Clarence Valley, Coffs Harbour City, Kyogle, Lismore City and Richmond Valley.

3:05pm: Thousands of travellers making their way home after the long weekend are facing delays and disruptions at Sydney Airport, as ex-tropical cyclone Oswald forces airlines to cancel flights.

Virgin Australia said it had cancelled twenty flights nationally on Tuesday, 16 of which were flying in and out of Sydney.

The majority of the flights affected are those to and from Brisbane, the Gold Coast, Canberra and Melbourne.

The Qantas group, including Jetstar, says the number of flights affected will not be known until later on Tuesday.

2:01pm: The Clarence River at Grafton appears to have peaked just 2cm below the top of the levee wall in the flood-hit northern NSW town.

Sam Colwell of the Clarence-Nambucca State Emergency Service says the river is believed to have peaked at midday (AEDT) on Tuesday, at a record level of 8.08 metres.

12:30pm: Premier Barry O'Farrell will fly to Grafton this afternoon to be briefed by the SES on the flood situation.

He is set to arrive about 2.30pm (AEDT) and will be joined by SES Commissioner Murray Kear.

Meanwhile the SES said it was rescuing four people trapped in a 4WD in floodwaters at Bellingen, southwest of Coffs Harbour.

11:05am: Several roads remain closed on the Central Coast after 197.2mm of rain was recorded at Gosford in the 24-hours to 9am this morning.

Wyong Shire Council said Minesota, Louisiana and Warnervale roads remain closed at Warnervale along with Durham Rd at Gorokan, Jilliby and Mandalong roads at Jilliby and Burns Rd, Ourimbah.

Water is also covering Shirley St at Ourimbah but the road remains open with motorists advised to exercise caution.

Carlton Rd and Milina Rd at Holgate remain closed either side of the Wattle Tree Rd intersection with Daley Av at Daleys Point re-opened after a landslip about 3am.

In addition to localised flooding the rain caused havoc for motorists with two people taken to hospital after a car flipped on the F3 at Mooney Mooney yesterday.

Police said the driver was only travelling about 90km/h in a 110km/h zone when the car began to fishtail before striking a dividing barrier and rolling onto its roof.

Another car braked heavily to avoid the vehicle but the trailer it was towing jack-knifed and hit a third car.

10.35am: More than 2500 people around Grafton in northern NSW have been ordered to evacuate amid fears of record flooding.

NSW State Emergency Service spokesman Phil Campbell said the Clarence River is expected to peak at just over 8m around midday (today, which could cause record flooding in the region.

9:59am: The mid north coast holiday town of Coffs Harbour has survived a horror night of wind and rain.

The city has escaped the aftermath of former cyclone Oswald with no homes or businesses flooded.

A few stray branches and fallen trees are all that remain after last night's storm.

A rescue is still underway in Grafton on the state's north coast, after 20 people called for help from one property on the Clarence River early this morning.

A State Emergency Services spokeswoman said a flood boat had been dispatched to rescue the group, though the exact circumstances of their situation were still unclear.

On Sydney's north shore, a couple whose 4WD got stuck in flood waters on Mona Vale Road in St Ives had to be rescued by crews about 5am.

Rain damageSource:The Daily Telegraph

There have been 3000 calls for help to the SES, most coming from the state's north coast.

Evacuation orders are in place for parts of Grafton and Lismore, with many of the 34 rescues conducted in the two towns.

The SES are warning people not to cross flood waters in their vehicles. For emergencies, call the SES on 132 500.

7.28am: Southern NSW is being told to prepare for driving rain and 100km/h winds as ex-tropical cyclone Oswald sparks evacuations in the state's north.

The NSW State Emergency Service says the focus will be on the south of the state on Tuesday, with a severe weather warning issued for Sydney, the Hunter and Central Coast, Illawarra and the south coast and parts of the Central Tablelands.

Rain damageSource:The Daily Telegraph

6.52am: While you were sleeping Sydney was smashed with a heavy downpour of rain which is predicted to continue this morning.

Two motorists who parked their cars on Elizabeth St, Artarmon last night will wake-up today and find a tree about eight-metres long on top of their vehicles as ex-tropical cyclone moves down to NSW.

The Mitsubishi Lancer and Holden Astra were crushed when dampened soil led to the tree uprooting and falling.

But the driver of a BMW 4WD had luckily parked his car on the opposite side of the road just out of reach of the fallen tree.

ArtarmonSource:The Daily Telegraph

On Northcote Rd, Glebe another tree also about eight metres narrowly missed parked cars when it fell across the road.

A portion of the Anzac Pde, Kensington was flooded when rainwater gathered across the bus lane and onto the pedestrian walkway.

One nearby business prepared for the threat of heavy rainfall by sandbagging the entrance to their offices.

Eastbound cars travelling on City West Link Rd overnight drove through a road flood in the left lane sending water more than two metres into the air.

There are also reports of some areas in Camden and Marrickville which experienced "isolated and localised'' flooding, a spokesman for the State Emergency Services said.

YESTERDAY: Frantic evacuations were under way in northern NSW last night as the cyclone left at least four people dead and a damage bill in the hundreds of millions of dollars.

Road floodSource:The Daily Telegraph

Shortly before midnight, in a tragic end to a day of devastation, a three-year-old boy died after a tree fell on him, taking the total number of people killed by the flood disaster to four.

As helicopter pilots made daring rooftop rescues in Bundaberg, Brisbane saw a return of the "mud army", helping to evacuate houses in scenes reminiscent of the city's devastating 2011 floods. See full story and photos here

Many were already recounting amazing rescue stories including that of little Luke Collie, the boy dubbed the 'baby in the bag' whose story of being winched to safety made world headlines.

SES crews were scrambling to doorknock more than 500 homes in Lismore, urging residents to either evacuate or prepare their homes for major flooding.

GlebeSource:The Daily Telegraph

Evacuations were also under way in Grafton. In Tweed, thousands fled as rapidly rising floodwaters inundated homes, cut roads and isolated entire communities yesterday.

"It is an evacuation warning, advising residents of the potential for flooding and telling them they need to either go to higher ground or prepare themselves," SES spokeswoman Jessica Chan said.

More than 2000 people remained isolated by rising floodwater last night, mostly in the saturated Richmond and Tweed Valley regions.

With it came a deluge that cut off entire communities, forced the closure of the Pacific Highway at Grafton and prompted more than a dozen flood rescues.

While most of Grafton is protected by 8m high levees built along the surging Clarence River, long time resident Maxine Gleeson feared the worst.

The 71-year-old, who has lived in Grafton all her life, said three days of continuous torrential rain could see the levee break overnight.

"It's a bit of a precarious situation. It's been raining really heavily, the wind has finally died down, but before that I was really frightened. It's the third night of torrential rain. Another night of heavy rain and who knows what's going to happen."

Bundaberg under waterSource:Supplied

Bureau of Meteorology forecaster Julie Evans said more than 900mm of rain had fallen on parts of the far north coast.

But the worst was yet to come for people further south.

The storm's main front was not due to hit Sydney until after midnight, Ms Evans said, with early morning downpours of up to 200mm likely across the city.

"There's always the possibility localised falls could be heavier but broad-scale, we're talking 100-200mm at this stage," she said. "The other thing to keep in mind is the potential for very strong wind gusts along the coastal fringe."

Specialist flood rescue crews were deployed to Sydney last night in anticipation of the wild conditions.

The SES recorded more than 1600 calls for help by early evening, including more than 300 from people directly affected by flooding.

Ms Chan said crews in the state's north were involved in 16 rescues, many involving motorists who ignored warnings and drove through flooded roads only to be swamped and stranded.

"Obviously these people are not heeding our warnings never to drive through floodwater," she said. "We really need people to understand the dangers and hazards they are facing - we can't stress that enough." Rising floods forced the closure of the Pacific Highway near Grafton yesterday morning, creating major delays for tens of thousands of motorists returning home for the end of school holidays.

Flood warnings remained in place for nine NSW rivers last night. Grafton, Lismore, Murwillumbah and Maclean are among the towns expected to see major flooding today.

It is more than a week since authorities downgraded Oswald from a category one cyclone to an ex-tropical cyclone, but it still produced wind speeds yesterday well in excess of 100km/h.

Farmers in the Clarence Valley spent much of yesterday getting their livestock to higher ground.

Erroll Chevelley and his siblings rounded up their 700 head of cattle for a 14km trek to safety.

"The important thing is to get them ahead of the flood tonight but we'll have to break tomorrow until one of the creeks goes down," he said. "Otherwise we'll have calves being washed away."

The swell peaked at almost 6m about noon, with a 10m wave recorded off Coffs at noon.

The search for for a swimmer missing since Saturday off the Central Coast was called off.

Surf Life Saving spokeswoman Donna Wishart said at least three surfers were rescued yesterday.

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